Oil Pressure Problems

[Boost All The Dollys]

Some interesting reading here on Jaguars AJV6 engine.

https://auto-tat.co.uk/AJ-V6%20Sump.html

Is your sump suitable baffled.

That’s some semi-useful info for others but not so much for me or other dolomites. The middle/rear sump from the X types or Mondeos would put the sump directly where the steering rack is.

That front extension is the main reason I made my own sump. It would be in the same place as the front anti-roll bar and although I swapped to an MX5 bar and moved it forward approx 2 inches, that still wouldn’t be enough.

What’s definitely interesting is the idea of a horizontal baffle plate to prevent oil from sloshing upwards. The original Jag sump had one so maybe something I should think about.

[Carledo]

When I designed the sump, I made sure to make that slope grater than the tilt of the engine for that reason. There also isn’t a baffle that would prevent the oil from building up on that surface.

And that isn’t something I realised about the Chevys. The oil pick up on this sits right at the back of the main well so that should help.

I have been thinking of remaking the sump (as well as a lot of other parts) so I could change some parts of it to increase its capacity. Maybe even change to a semi-dry sump system.

Thank you very much for the advice. Definitely given me a lot to think about.

I also thought of suggesting a dry sump design, that way your oil capacity wouldn't be constrained by space! It also occurred to me that a standard design would have the oil level below that slope (the slope is no help if the stationary oil level is above it) which, on the face of it, would reduce your current oil capacity to completely unacceptable levels. The 8v Vauxhall engine I use has a baffle plate built into the sump gasket, effectively a metal base plate with only a couple of holes in it and the rubber gasket wrapped around the edge, specifically designed I imagine to counter any surge.

You also might want to consider something I was forced into by my decision to not mess with the sump. The front of the sump was unfeasibly close to the front crossbeam of the subframe and the very forward mounting for the oil filter actually interfered with it so I chopped it out and made a forward extension piece out of 50x25x2mm box section steel. (I can provide a drawing with measurements should you wish to duplicate this) This occupied the space normally used by the antiroll bar, so I remounted the ARB BELOW the tie bars at the outer ends and relocated the central mounts under the new extension piece. This has worked perfectly for many years on both my cars.




I'll try and get a more comprehensive explanatory pic or two tomorrow.

Steve

[Boost All The Dollys]

That is pretty much what I’ve done with mine. The front of the sump occupies the space where the front cross member would be. I cut the whole thing out to have clearance elsewhere and added a brace which bolts to the ARB holes. This brace is pretty stout and also serves as the new ARB mount and lower radiator mount.

But I’d never thought about just flipping the roll bar to lower it. My current issue is that the most forward part of the engine is actually the drivers side exhaust manifold. There wasn’t enough space to run it elsewhere so had to run it in front of the alternator so the brace is a bit thinner at that section. If I wanted to, the brace could be made to be the same thickness all the way along and it would give me an extra inch or two in front of the engine to expand the sump into it but before I did that, I’d want to strengthen the subframe more in other areas.

I could just add an expansion that sat underneath the brace but I don’t know how much volume that would add. Just to note, the bottom of the brace is about level with the bottom of the front valance, so there’s space to add another wing to the front for more volume.

I have just had the thought of adding some sort of oil tank to the underside of the brace or even the brace itself becoming the oil tank.

[cliftyhanger]

I would be testing the sump "efficiency" before doing anything to it. Jacking the car up at the rear would direct the oil faster into the sump bowl, and while stationary would eliminate any surge issues.
The oil pickup has been modified, I am assuming it was carefully checked for any leaks/restrictions etc?

[SprintV8]

What’s behind the plate that’s says do not remove.
Is it just a for the extra oil capacity.
Do you still have the original sump.
Is there something diverting some of the oil like a bypass?
Yes I’m fully aware of the difference in sump types.
It was mostly about the oil starvation and baffles.

[Boost All The Dollys]

What’s behind the plate that’s says do not remove.
Is it just a for the extra oil capacity.
Do you still have the original sump.
Is there something diverting some of the oil like a bypass?
Yes I’m fully aware of the difference in sump types.
It was mostly about the oil starvation and baffles.

I’ve no clue what’s behind there. Seeing as it says do not remove, I imagine it’s there purely for manufacturing reasons. And yeah, that did pique my interest, something I’ll definitely think about adding is a horizontal baffle as well.



On another note, the more I think about this issue, the more I’m leaning towards the main problem being oil quantity that’s causing the spin bearings. As there is very little room to make my sump bigger without substantial changes, I think I’m going to add either an extension to the front of the sump or a separate oil tank mounted just in front, I’ve just got to measure some things first to check clearance and volume. If I’ve remembered the measurements right, I could add an oil tank that would add an extra 2.25L just in front of the sump without much effort so I think I’ll do that.

[SprintV8]

I still think you may have also a low oil pressure problem.
And low oil capacity.
Difficult to find any pressure info on line.

There’s a jaguar specialist that I occasionally drop off to.
If I remember I’ll ask next time I go in there.

[Boost All The Dollys]

That would be amazing, thank you. There isn’t a Jaguar garage local to me, nearest one is over an hour away and I don’t know if they would know that.

I also found out while I was fiddling around with the oil lines that I had got them backwards, so the oil filter was being used backwards, which might have contributed to my dodgy oil pressure AND my oil flow problems. I know they have a pressure relief valve in so it might have been running through that which wouldn’t have been a big passageway, which probably caused some cavitation at higher flow speeds !

I’ve also been and taken a load of measurements of my sump and the surrounding area. Don’t think I’ll have the space for a practically sized additional oil tank so I think the most appropriate course of action is to remake the front crossmember to be thinner and make a new sump. As easy as it would be to modify my current sump, with what I need to do to it, it’ll be much easier to just make a new one.

What I’m going to do is make a new one that’s similar to the old one but increase its depth a little bit, extend the front of the well, and level the bottom of the sump off. This will get me the extra 2L I need and there’s enough space to expand it an additional litre if needed. This in conjunction with the slightly lower oil pickup should definitely help with the oil feeding problems.

[xvivalve]

I ran your woes past a pal who works for a Jaguar parts specialist. His opinion is at warm idle oil pressure should be in the 25-35 range and it doesn't take much reduction from that to run the bearings. A good quality 5-30 semi-synthetic is all he'd use himself excepting for Mobil 1 0140; a thicker oil is folly as some of the galleries are very small! The Jag v6 has common crank issues; the blocks are apparently stamped and coded on original assembly to identify what bearings have been fitted and replacement bearings are sold as individual shells rather than as a crank set!! Care therefore needs to be taken if replacing bearings to ensure the correct spec are fitted. He doesn't recall ever having received an order for an oil pump for these engines, but he did say that they've been so commonly available a lot of folk who experience problems simply source a complete known good engine! A common cause of low oil pressure is a clogged pick up and he agreed that if surge removed the reservoir of oil from the pick up position it could intermittently starve the engine, but this wouldn't cause constant low pressure; he cautioned that a lot of X and S Type drivers were aged and used their cars to potter to the golf club and back...and when they start getting driven 'properly' faults become apparent! Have you fitted an oil pressure warning light?

[Carledo]

I also found out while I was fiddling around with the oil lines that I had got them backwards, so the oil filter was being used backwards, which might have contributed to my dodgy oil pressure AND my oil flow problems. I know they have a pressure relief valve in so it might have been running through that which wouldn’t have been a big passageway, which probably caused some cavitation at higher flow speeds !

I'm not quite sure what this would do to the engine, but i'm sure it's nothing good and may well be the main cause of your problem! Bit of a "D'oh" moment for you, no doubt!

However I do think you still need to explore a bit of extra sump capacity and a horizontal baffle to counter surge. If Alun's guy says the oil pressure SHOULD be considerably higher i'll believe it, a lower specified pressure was only an idea I got from knowing the ridiculously low running pressure used on the Rover unit.

Steve

[Boost All The Dollys]

I ran your woes past a pal who works for a Jaguar parts specialist. His opinion is at warm idle oil pressure should be in the 25-35 range and it doesn't take much reduction from that to run the bearings. A good quality 5-30 semi-synthetic is all he'd use himself excepting for Mobil 1 0140; a thicker oil is folly as some of the galleries are very small! The Jag v6 has common crank issues; the blocks are apparently stamped and coded on original assembly to identify what bearings have been fitted and replacement bearings are sold as individual shells rather than as a crank set!! Care therefore needs to be taken if replacing bearings to ensure the correct spec are fitted. He doesn't recall ever having received an order for an oil pump for these engines, but he did say that they've been so commonly available a lot of folk who experience problems simply source a complete known good engine! A common cause of low oil pressure is a clogged pick up and he agreed that if surge removed the reservoir of oil from the pick up position it could intermittently starve the engine, but this wouldn't cause constant low pressure; he cautioned that a lot of X and S Type drivers were aged and used their cars to potter to the golf club and back...and when they start getting driven 'properly' faults become apparent! Have you fitted an oil pressure warning light?

Yeah, I double checked when I ordered the bearings which size to order and bought the right size. It’s annoying as one set of numbers is stamped on the block and PRINTED on the crankshaft so i had to be careful not to accidentally wipe them off when cleaning the face to see what the numbers were.

And I have the standard oil pressure warning switch from the engine, I think it’s about 5psi activation.

I’ll try going back to a 5w30 oil just to be sure.

I'm not quite sure what this would do to the engine, but i'm sure it's nothing good and may well be the main cause of your problem! Bit of a "D'oh" moment for you, no doubt!

However I do think you still need to explore a bit of extra sump capacity and a horizontal baffle to counter surge. If Alun's guy says the oil pressure SHOULD be considerably higher i'll believe it, a lower specified pressure was only an idea I got from knowing the ridiculously low running pressure used on the Rover unit.

Steve

Very much a D’oh moment, couldn’t believe I’d gotten it wrong. And I’m very much still exploring extra capacity in the sump. It’s just very difficult with how little space there is around the sump. Like I’ve mentioned before, I have a few options available to me, the most efficient one just happens to also involve the most amount of work. It could be that the low pressure I’m seeing is the pressure left over after the oil has passed through whatever bypass/relief valve is in the oil filter, which is why it’s never changing with rpm. The relief valve in the pump is only maintaining the pressure between the pump and the filter and the gauge is only measuring pressure after the filter. And the valve in the filter can only flow 20psi worth of oil

Seeing as the car is laid up for the winter, I might as well pull the engine to sort this and a host of other issues out at the same time.

Thank you all for your help

[cliftyhanger]

I also found out while I was fiddling around with the oil lines that I had got them backwards, so the oil filter was being used backwards, which might have contributed to my dodgy oil pressure AND my oil flow problems. I know they have a pressure relief valve in so it might have been running through that which wouldn’t have been a big passageway, which probably caused some cavitation at higher flow speeds !

If you used a filter with an anti-drain valve that would definately cause the issues you describe.

Years ago I built a sprint powered spitfire. That was a great car, the lady wife drove it until she was too pregnant to get behind the. We then sold it, and some time later the chap had some work done by a "mechanic". Shortly after the big ends failed. The mechanic said the remote oil filter had been connected the wrong way round by me. Cheeky bugger, we did about 20k and it was fine. But the issue sounds remarkably similar...

[Boost All The Dollys]

If you used a filter with an anti-drain valve that would definately cause the issues you describe.

Years ago I built a sprint powered spitfire. That was a great car, the lady wife drove it until she was too pregnant to get behind the. We then sold it, and some time later the chap had some work done by a "mechanic". Shortly after the big ends failed. The mechanic said the remote oil filter had been connected the wrong way round by me. Cheeky bugger, we did about 20k and it was fine. But the issue sounds remarkably similar...

Yeah, think I’ve solved it now.

Been and worked on it today, refitted the sump and oil lines (in the correct layout) and stuck the starter motor on with the spark plugs removed and the cold cranking pressure on the gauge was around 60-70psi, which is around 20psi greater than what it used to be. So, think I’ve solved the problem of oil flow. No idea how the engine has lasted this long like that, must have been just enough pressure to hold together.

Well, thank you all for your help and knowledge, it’s been very much appreciated, I owe you all a drink or two

[SprintV8]

Well it appears to have found what was the low oil pressure problem.

I suppose if you work it out like a thermostat in a cooling system you’re trying to push the coolant the wrong way.
Some coolant will flow but not much.
Swap the hoses round and bingo full flow.

These things are sent to try us.

Just seen on you tube a MK3 Escort Rally car with a Jaguar 3lt V6 Rear wheel drive.


Mercedes use coloured marking on the shells.
Blocks and crankshafts are physically stamped with three letters.

[SprintV8]

Just had a quick chat today.
They say max 50psi hot at any revs.
Anything more than that they start leaking oil.